In a liquid crystal display device, a TFT substrate over which pixel electrodes and thin-film transistors (TFTs), inter alia, are formed in a matrix and an opposing substrate over which color filters, inter alia, are formed in positions corresponding to the pixel electrodes in the TFT substrate are placed facing each other and liquid crystals are sandwiched between the TFT substrate and the opposing substrate. An image is produced by controlling light transmissibility through liquid crystal molecules pixel by pixel.
An upper polarizing plate is attached to the upper surface of the opposing substrate and the upper polarizing plate is prone to damage because it is made of resin. As a countermeasure against this, a front window made of glass is often put over the opposing substrate. An arrangement is used in which the front window is positioned apart from the liquid crystal display panel in order to provide mechanical protection for the liquid crystal display panel, as shown in FIG. 8.
In the case of related art as typified in FIG. 8, a problem of ghost image appearance arises. FIG. 8 is an explanatory diagram about ghost image appearance, taking a reflective liquid crystal display panel as an example. In FIG. 8, an incoming external light beam L passes through the front window 30 and is reflected by the liquid crystal display panel. After passing back through the front window 30 again, it enters a human eye. Although the external light beam L is refracted by the front window 30, this refraction is here ignored in FIG. 8.
A part of the light beam reflected at a point P1 on the front surface of the liquid crystal display panel is reflected back by the undersurface Q1 of the front window 30 and comes at and is reflected again by a point P2 on the front surface of the liquid crystal display panel. When the human views the light beam reflected by the point P2, the phenomenon of ghost image appearance takes place. Although FIG. 8 explains ghost image appearance taking the reflective liquid crystal display panel as an example, this is also true for a transmissive type. That is, in the transmissive type, when a light beam transmitted through the liquid crystal display panel travels at the same angle as the light beam reflected at the point P1 on the front surface of the liquid crystal display panel, it is reflected back by the undersurface Q1 of the front window 30 and follows the same path as shown for the reflective type. This phenomenon of ghost image appearance deteriorates image quality.
Another problem that is encountered by a liquid crystal display panel is that light is reflected from the edge faces of the TFT substrate 10 and the opposing substrate 20 and radiated from the display region, which degrades the contrast of the screen. To take a countermeasure against this problem, “Japanese Published Unexamined Patent Application No. 2003-5160” discloses an arrangement in which the edge faces of the TFT substrate 10 and the opposing substrate 20 are shielded from light to prevent light reflection from the edge faces. In “Japanese Published Unexamined Patent Application No. 2003-5160”, however, there is no disclosure about the front window and there is no description about light leakage in the margins of the screen due to the front window.